Article focus
Recent evidence suggests that vitamin D3 has potent extraskeletal effects, such as suppression of inflammation and strengthening of mucosal immunity by induction of antimicrobial peptides.
Data from observational studies suggest that low levels of 25-hydroxyvitamin D3 are associated with an increased risk of respiratory tract infections.
Results from a limited number of randomised controlled trials on the protective role of vitamin D3 against respiratory tract infections are inconclusive and thus additional studies are warranted.
Key messages
Therefore we designed and carried out a randomised controlled trial where a large dose (4000 IU) of vitamin D3 was given to patients with an increased susceptibility to infections for 1 year.
The main conclusion is that vitamin D3 supplementation reduces symptoms and antibiotic consumption among patients with an increased frequency of respiratory tract infections. Thus, vitamin D3 supplementation may be an alternative strategy to reduce antibiotic use among patients with recurrent respiratory tract infections.
Strengths and limitations of this study
A high daily dose of vitamin D3 was used, the study time was a full year covering all seasons and patients with an increased frequency of respiratory tract infections were studied.
A single study centre, small sample size (n=140) and a selected group of patients.